Hirabayashi A, Sakairi M, Koizumi H
Central Research Laboratory, Hitachi, Ltd., Tokyo, Japan.
Anal Chem. 1995 Sep 1;67(17):2878-82. doi: 10.1021/ac00113a023.
We have developed a sonic spray ionization method, in which a methanol and water solution is sprayed from a fused-silica capillary with gas flow coaxial to the capillary. Ions as well as charged droplets are produced under atmospheric pressure, and their intensities depend on the gas flow rate (gas velocity). Positive ions produced from dilute solutions of molecules regarded as neurotransmitters, such as catecholamine, by this ionization method have been analyzed with a quadrupole mass spectrometer. The protonated dopamine molecule is detected in the spray of the 10 nM solution, and the mass spectrum is compared with that obtained by the ion spray ionization method. A comparison between the mass-analyzed ion intensity and the ion current, which represents the sum of ions and charged droplets, shows that most ions are produced from the charged droplets after spraying. Furthermore, we found that the charged droplet formation cannot be ascribed to the traditional models of friction electrification, electrical double layer, or statistical charging. An explanation is proposed based on the ion concentration distribution in a small droplet.
我们开发了一种超声喷雾电离方法，其中甲醇和水溶液从熔融石英毛细管中喷出，气流与毛细管同轴。在大气压下产生离子以及带电液滴，它们的强度取决于气体流速（气体速度）。通过这种电离方法从被视为神经递质的分子（如儿茶酚胺）的稀溶液中产生的正离子，已用四极杆质谱仪进行了分析。在10 nM溶液的喷雾中检测到质子化多巴胺分子，并将质谱与通过离子喷雾电离方法获得的质谱进行比较。质量分析离子强度与代表离子和带电液滴总和的离子电流之间的比较表明，大多数离子是在喷雾后从带电液滴中产生的。此外，我们发现带电液滴的形成不能归因于摩擦起电、双电层或统计充电的传统模型。基于小液滴中的离子浓度分布提出了一种解释。
